Question: When did Arthur B. Langlie become Seattle's head of government and when did he stop?
Paraphrase: When did Arthur B. Langlie turn out to be Seattle's head of government and when did he stop?
SPARQL (Wikidata): SELECT ?value1 ?value2 WHERE { wd:Q5083 p:P6 ?s . ?s ps:P6 wd:Q371494 . ?s pq:P2032 ?value1 . ?s pq:P2031 ?value2 }